The horizontal slats of a venetian blind are typically held in spaced relation to one another by two or more ladder tapes which are supported by an assembly mounted near the top of a window opening. The assembly generally includes a tilt rod and two or more tape drums for connecting the free ends of the ladder tape to the tilt rod. As a tilt mechanism is operated to rotate the tilt rod, the tape drum rotates with it. As a result, one side of the ladder tape is raised while the other side is lowered, thereby causing the venetian blind slats to tilt about their longitudinal axes.
The assembly of the ladder tapes to the tape drums has heretofore been a difficult and very labor-intensive process. In one such process, the tape drum is first assembled onto the tilt rod which is then assembled inside of the venetian blind headrail. Subsequently, the free ends of the ladder tape are assembled to the tape drum. This assembly process is extremely difficult and slow since the individual performing the assembly must work within the confines of the headrail in order to assemble the ladder tape to the tape drum.
In order to obviate this difficulty, tape drums have been developed in which the ladder tape is first assembled to the tape drum, after which the tape drum is press fit onto the tilt rod which has already been assembled in the headrail. In one form of tape drum, shown in FIGS. 1 and 2, which is currently available for use in this assembly technique, the free ends of the ladder tape are fitted with metal clips which are securely held in place in the tape drum. While this assembly technique makes it much easier to connect the tape drum to the tilt rod, other assembly difficulties are created thereby. Firstly, this assembly method is relatively costly in that it requires a full inventory of metal clips to be maintained, as well as a ready supply of hand tools for assembling the clips to the ladder tape. Also, the need to first attach the clips to the ladder tapes adds an extra step in the venetian blind assembly process. Furthermore, the crimping of the metal clips to the ladder tape requires a significant amount of hand strength, and this therefore becomes more difficult towards the end of the work shift as the assemblers' hands begin to tire. Moreover, assemblers who have performed the crimping process over extended periods of time have experienced numerous medical problems. More significant among these is carpal tunnel syndrome, the treatment of which has oftentimes required surgery, and which therefore has resulted in increased medical and insurance costs to manufacturers in addition to the increased costs associated with having to train new employees in the requisite assembly skills.
There therefore exists a need for an improved tape drum which will overcome the numerous deficiencies of the tape drums which are currently available. In particular, the need exists for a tape drum to which a ladder tape may be readily connected outside of a venetian blind headrail, and which can then be readily connected in assembled position to a tilt rod inside of the venetian blind headrail.